It has been proposed that programmable machines be used in the high speed manufacture of consumable products such as foods, detergents and toiletries. Such products are produced by operations which may be carried out at repetition speeds of up to hundreds of operations per minute. Typical manufacture operations for such products include dosing and mixing of materials, and shaping and heat treatment operations when preparing a wide variety of foodstuffs. Packaging such as carton erection and sealing, plastic pouch forming and filling and bottle filling and labelling are also areas in which programable machines have applications.
At present such manufacture requires the use of dedicated machines which are capable only of producing a single product and such a traditional machine usually includes a central electric motor and gear box together with cams, levers and eccentrics for producing the various required motions of its constituent parts. Naturally, such a machine can be designed and built to perform almost any specific task and, by changing the gearing or the cams, levers and eccentrics can be tailored to produce a different size or shape of product or to produce a different product. Naturally, changing such a dedicated machine to produce a different product requires a considerable amount of time and the expertise of a skilled fitter.
Robot arms are now being generally used in industry but only for the handling and assembly of high-value, low volume goods. Such robot arms can be programmed to perform a variety of different movements and so carry out a variety of different operations in response to their programming software. In general, robot arms operate only slowly.
The proposed programmable machine includes a number of actuators, each of which produces controlled movement along a different linear axis, produces controlled rotation, or produces controlled delivery of a particular one of a range of material or, for example, produces controlled quantity of any particular materials to be supplied. The operation of all of the individual actuators is controlled by a computer so that entire operating movements of the machine are controlled by software stored in or fed to the computer Such a machine is then capable of changing from the manufacture of one particular product to another by giving an instruction to the computer. Such a machine has considerable flexibility and is able to cope not only with changes from one product to another, but is also able to cope with the changes of a feed back nature to change the operation of the machine to take account of changes in the characteristics of the basic materials being handled by it.
Taking as a specific example the case of a pizza production line: This typically consists of a conveyor to move a prepared pizza base between various application stations. At a first station the pizza bases are placed on the conveyor in a predetermined location and at subsequent stations tomato paste is spread over the surface of a pizza base and this is followed by the application of other particular ingredients depending on the nature of the pizza being produced. The layout or pattern in which the various ingredients are arranged on the pizza base may also need to be varied depending on the particular variety of pizza being manufactured.
A programmable machine for producing such pizzas would have to be capable of handling a variety of different sizes of pizza base and work stations driven by actuators which dispense tomato paste and the other ingredients and place them on the surface of the pizza would have to apply them over the required area dpending upon the size of the pizza base. The machine would also have to supply different quantities of the ingredients for different sizes of base.
Another example of a machine which it would be desirable to produce as a programmable machine is a carton erecting machine. In such a machine, the position of the guide rails and the extent of movement of its various actuators would have to be varied with the size of carton being erected, as would the movement and quantity of glue supplied by a glue applicator. For such a machine the size, shape or style of carton being erected could be changed simply by an instruction to the computer of the machine, although it may also be necessary to supply a different carton blank.
Whilst such programmable machines have been proposed and attempts have been made to produce prototypes, programmable machines are not yet available which are capable of being used in production. Partly this is due to the time taken for a computer to interact with a number of actuators and sensors to control their movement in real time. This time increases with increases in the number of actuators and the resulting bus contention and when a particular profile of movement is required to be calculated for each actuator operation. With such constraints it has not been possible so far to produce a multi-axis programmable machine which is capable of operating at high speed. Another, and probably more serious problem is that such machines require specialist computer programmers to prepare the computer programs that control their operation. It is naturally desirable to have a simple control system for such a machine to enable a typical production engineer with no specialist knowledge of computers or computer programming to be able to set up the required instructions for such a machine.